body {
  max-width: 640px;
  min-width: 320px;
  margin: 0 auto;
  padding: 0;
}
img {
  width: 100%;
}
.banner {
  position: relative;
}
.banner .b-wz {
  position: absolute;
  right: 55px;bottom:75px;
  width: 50%;
}
.b-wz img {
  /*width: 50%;*/
}